The free maximization of profits was the basic motive force of individualist farming and the most powerful dissolvent of the moral and communal ethic that has guided economic affairs in medieval times. The characteristic structural forms encouraged by commercialization were the enclosure and engrossing of holdings. This involved another notable change in the physical environment, as well as a reordering of the agrarian scene. The enclosure of the fields of Tetchwick, Buckinghamshire, by 1519 escaped official notice and Peter Brandon talks of the 'silent revolution' by which most of the open fields of Sussex were enclosed during the sixteenth and early seventeenth centuries, un-chronicled in surviving documents. The crucial transition occurred during the second half of the seventeenth century, when communalism ceased to reflect the orthodox economic philosophy and the dominant shape of farming on the ground. Common field agriculture no longer defined the character of the agrarian scene as it had done in medieval times.